A pressure washer is a device that outputs a high-pressure jet of water that can be used to wash surfaces such as wood, tile, concrete, etc. Many pressure washers are powered by electricity and designed for household and light commercial use. Such an electrical pressure washer typically includes an electrical motor for pressurizing water from a low-pressure source (e.g., a garden hose) to a much higher pressure. The pressurized water then goes through a flexible hose to an application wand (or lance), which is fitted with a nozzle with a fixed or variable aperture and has a trigger for turning high-pressure water jet on or off. To enhance the cleaning power of the water stream, some pressure washers have a chemical tank for storing a liquid detergent and have an operation mode in which the detergent is extracted from the tank by means of vacuum suction and mixed into the water stream.
Although an electrical pressure washer is a relatively simple device, its operation may be affected by various conditions and may appear to an inexperienced user to be malfunctioning even if the machine is actually in good shape. For instance, an electrical pressure washer may be required by safety code or regulations to be equipped with a ground fault circuit interrupter (GFCI) for protecting a user from electrical shocks. A GFCI, however, may sometimes be accidentally tripped, and the AC power to the motor will be cut off as a result. In such a situation, the pressure washer can be put back in operation by simply resetting the GFCI. Nevertheless, an inexperienced user who is unaware of the existence and/or function of the GFCI may think that pressure washer is broken. As another example, when the pressure washer is put in the chemical suction mode, the pressure of the water jet is significantly lower than that in the normal operation mode. A user, however, may not know or remember to check that the pressure washer is in the chemical suction mode and may jump to the conclusion that the pressure washer is defective. Also, the pressure washer will not work properly if the AC voltage supplied to it is low, which may happen if the user plugs the pressure washer into a long extension cord, which introduces a substance voltage drop due to the large amount of current drawn by the pressure washer.
Thus, inexperienced users often find it difficult to identify the reasons why their electrical pressure washers do not work as expected. Such difficulties present a serious problem to the manufacturer of the pressure washers due to the increased cost for providing consumer services. When a user plugs in a newly purchased pressure washer and does not get the expected high-pressure water jet, he may think that the machine is defective and decide to return it to the store where he bought it. The allegedly bad machine is then returned the manufacturer even if it is fully functional. A user may also call in for service under warranty when his pressure washer stops pumping water. As a result, a service technician may have to be dispatched to service the machine in the field, even if the problem can be simply corrected by resetting the GFCI switching from the chemical suction mode to the normal operation mode, or removing the extension cord, etc.